Under a fiat standard interest is charged on debt created out of thin air. This inherently requires the creation of additional money to pay the interest, leading to inflation.

Under a bitcoin standard interest would be charged on a finite asset which causes the debtor to chase an ever growing financial burden.

Neither scenario is conducive to a fair, just, or ethical society.

Both result in money lenders turning the rest of the population into serfs or debt slaves.

The alternative would be to loan bitcoin for a percentage of the enterprise being proposed. This aligns the incentives of the debtor with the debtee and does not result in debt slavery.